Conventionally known is an injection molding machine which is designed so that an overall screw movement section is divided into a plurality of subsections, an injection speed is set for each screw movement subsection; and injection operation is controlled to equalize the screw moving speed for each screw movement subsection to the injection speed for each subsection. However, the conventional injection molding machine has a problem in that the screw moving speed within equally divided sections remains constant regardless of the screw position, so that the injection speed changes by stages like a Gauss function, and thus it is hard for the speed to be changed smoothly.
In order for the injection speed to be changed smoothly by setting injection speeds by stages, it is necessary first to divide the screw movement section into considerably smaller subsections and then to assign different injection speeds individually to a number of smaller screw movement subsections obtained by the division, which is an extremely time-consuming task.